#include "pdsp_defs.h"
#include "util.h"

void
pdgssv(int nprocs, SuperMatrix *A, int *perm_c, int *perm_r, 
       SuperMatrix *L, SuperMatrix *U, SuperMatrix *B, int *info )
{
/*
 * -- SuperLU MT routine (version 1.0) --
 * Univ. of California Berkeley, Xerox Palo Alto Research Center,
 * and Lawrence Berkeley National Lab.
 * August 15, 1997
 *
 * Purpose
 * =======
 *
 * pdgssv() solves the system of linear equations A*X=B, using the parallel
 * LU factorization routine pdgstrf(). It performs the following steps:
 *
 *   1. If A is stored column-wise (A->Stype = NC):
 *
 *      1.1. Permute the columns of A, forming A*Pc, where Pc is a 
 *           permutation matrix. 
 *           For more details of this step, see sp_preorder.c.
 *
 *      1.2. Factor A as Pr*A*Pc=L*U with the permutation Pr determined
 *           by Gaussian elimination with partial pivoting.
 *           L is unit lower triangular with offdiagonal entries
 *           bounded by 1 in magnitude, and U is upper triangular.
 *
 *      1.3. Solve the system of equations A*X=B using the factored
 *           form of A.
 *
 *   2. If A is stored row-wise (A->Stype = NR), apply the above algorithm
 *      to the tranpose of A:
 *
 *      2.1. Permute columns of tranpose(A) (rows of A),
 *           forming transpose(A)*Pc, where Pc is a permutation matrix. 
 *           For more details of this step, see sp_preorder.c.
 *
 *      2.2. Factor A as Pr*transpose(A)*Pc=L*U with the permutation Pr
 *           determined by Gaussian elimination with partial pivoting.
 *           L is unit lower triangular with offdiagonal entries
 *           bounded by 1 in magnitude, and U is upper triangular.
 *
 *      2.3. Solve the system of equations A*X=B using the factored
 *           form of A.
 * 
 *   See supermatrix.h for the definition of "SuperMatrix" structure.
 *
 *
 * Arguments
 * =========
 *
 * nprocs (input) int
 *        Number of processes (or threads) to be spawned and used to perform
 *        the LU factorization by pdgstrf(). There is a single thread of
 *        control to call pdgstrf(), and all threads spawned by pdgstrf()
 *        are terminated before returning from pdgstrf().
 *
 * A      (input) SuperMatrix*
 *        Matrix A in A*X=B, of dimension (A->nrow, A->ncol), where
 *        A->nrow = A->ncol. Currently, the type of A can be:
 *        Stype = NC or NR; Dtype = _D; Mtype = GE. In the future,
 *        more general A will be handled.
 *
 * perm_c (input/output) int*
 *        If A->Stype=NC, column permutation vector of size A->ncol,
 *        which defines the permutation matrix Pc; perm_c[i] = j means 
 *        column i of A is in position j in A*Pc.
 *        On exit, perm_c may be overwritten by the product of the input
 *        perm_c and a permutation that postorders the elimination tree
 *        of Pc'*A'*A*Pc; perm_c is not changed if the elimination tree
 *        is already in postorder.
 *
 *        If A->Stype=NR, column permutation vector of size A->nrow
 *        which describes permutation of columns of tranpose(A) 
 *        (rows of A) as described above.
 * 
 * perm_r (output) int*,
 *        If A->Stype=NR, row permutation vector of size A->nrow, 
 *        which defines the permutation matrix Pr, and is determined 
 *        by partial pivoting.  perm_r[i] = j means row i of A is in 
 *        position j in Pr*A.
 *
 *        If A->Stype=NR, permutation vector of size A->ncol, which
 *        determines permutation of rows of transpose(A)
 *        (columns of A) as described above.
 *
 * L      (output) SuperMatrix*
 *        The factor L from the factorization 
 *            Pr*A*Pc=L*U              (if A->Stype=NC) or
 *            Pr*transpose(A)*Pc=L*U   (if A->Stype=NR).
 *        Uses compressed row subscripts storage for supernodes, i.e.,
 *        L has types: Stype = SCP, Dtype = _D, Mtype = TRLU.
 *
 * U      (output) SuperMatrix*
 *	  The factor U from the factorization
 *            Pr*A*Pc=L*U              (if A->Stype=NC) or
 *            Pr*transpose(A)*Pc=L*U   (if A->Stype=NR).
 *        Use column-wise storage scheme, i.e., U has types:
 *        Stype = NCP, Dtype = _D, Mtype = TRU.
 *
 * B      (input/output) SuperMatrix*
 *        B has types: Stype = DN, Dtype = _D, Mtype = GE.
 *        On entry, the right hand side matrix.
 *        On exit, the solution matrix if info = 0;
 *
 * info   (output) int*
 *	  = 0: successful exit
 *        > 0: if info = i, and i is
 *             <= A->ncol: U(i,i) is exactly zero. The factorization has
 *                been completed, but the factor U is exactly singular,
 *                so the solution could not be computed.
 *             > A->ncol: number of bytes allocated when memory allocation
 *                failure occurred, plus A->ncol.
 *   
 */
    trans_t  trans;
    NCformat *Astore;
    DNformat *Bstore;
    SuperMatrix *AA; /* A in NC format used by the factorization routine.*/
    SuperMatrix AC; /* Matrix postmultiplied by Pc */
    int i, n, panel_size, relax;
    yes_no_t refact, usepr;
    double diag_pivot_thresh, drop_tol;
    void *work;
    int lwork;
    pdgstrf_options_t pdgstrf_options;
    Gstat_t  Gstat;
    double   t; /* Temporary time */
    double   *utime;
    flops_t  *ops, flopcnt;

    /* ------------------------------------------------------------
       Test the input parameters.
       ------------------------------------------------------------*/
    Astore = A->Store;
    Bstore = B->Store;
    *info = 0;
    if ( nprocs <= 0 ) *info = -1;
    else if ( A->nrow != A->ncol || A->nrow < 0 || 
	      (A->Stype != NC && A->Stype != NR) ||
	      A->Dtype != _D || A->Mtype != GE )
	*info = -2;
    else if ( B->ncol < 0 || Bstore->lda < MAX(1, A->nrow) ) *info = -7;
    if ( *info != 0 ) {
        i = -(*info);
	xerbla_("pdgssv", &i);
	return;
    }

#if 0
    /* Use the best sequential code. 
       if this part is commented out, we will use the parallel code 
       run on one processor. */
    if ( nprocs == 1 ) {
        return;
    }
#endif

    refact = NO;
    trans  = NOTRANS;
    panel_size = sp_ienv(1);
    relax = sp_ienv(2);
    diag_pivot_thresh = 1.0;
    usepr = NO;
    drop_tol = 0.0;
    work = NULL;
    lwork = 0;

    /* ------------------------------------------------------------
       Allocate storage and initialize statistics variables. 
       ------------------------------------------------------------*/
    n = A->ncol;
    StatAlloc(n, nprocs, panel_size, relax, &Gstat);
    StatInit(n, nprocs, &Gstat);
    utime = Gstat.utime;
    ops = Gstat.ops;

    /* ------------------------------------------------------------
       Convert A to NC format when necessary.
       ------------------------------------------------------------*/
    if ( A->Stype == NR ) {
	NRformat *Astore = A->Store;
	AA = (SuperMatrix *) SUPERLU_MALLOC( sizeof(SuperMatrix) );
	dCreate_CompCol_Matrix(AA, A->ncol, A->nrow, Astore->nnz, 
			       Astore->nzval, Astore->colind, Astore->rowptr,
			       NC, A->Dtype, A->Mtype);
	trans = TRANS;
    } else if ( A->Stype == NC ) AA = A;

    /* ------------------------------------------------------------
       Initialize the option structure pdgstrf_options using the
       user-input parameters;
       Apply perm_c to the columns of original A to form AC.
       ------------------------------------------------------------*/
    pdgstrf_init(nprocs, refact, panel_size, relax,
		 diag_pivot_thresh, usepr, drop_tol, perm_c, perm_r,
		 work, lwork, AA, &AC, &pdgstrf_options, &Gstat);

    /* ------------------------------------------------------------
       Compute the LU factorization of A.
       The following routine will create nprocs threads.
       ------------------------------------------------------------*/
    pdgstrf(&pdgstrf_options, &AC, perm_r, L, U, &Gstat, info);

    flopcnt = 0;
    for (i = 0; i < nprocs; ++i) flopcnt += Gstat.procstat[i].fcops;
    ops[FACT] = flopcnt;

#if ( PRNTlevel==1 )
    printf("nprocs = %d, flops %e, Mflops %.2f\n",
	   nprocs, flopcnt, flopcnt/utime[FACT]*1e-6);
    printf("Parameters: w %d, relax %d, maxsuper %d, rowblk %d, colblk %d\n",
	   sp_ienv(1), sp_ienv(2), sp_ienv(3), sp_ienv(4), sp_ienv(5));
    fflush(stdout);
#endif

    /* ------------------------------------------------------------
       Solve the system A*X=B, overwriting B with X.
       ------------------------------------------------------------*/
    if ( *info == 0 ) {
        t = SuperLU_timer_();
	dgstrs (trans, L, U, perm_r, perm_c, B, &Gstat, info);
	utime[SOLVE] = SuperLU_timer_() - t;
	ops[SOLVE] = ops[TRISOLVE];
    }

    /* ------------------------------------------------------------
       Deallocate storage after factorization.
       ------------------------------------------------------------*/
    pdgstrf_finalize(&pdgstrf_options, &AC);
    if ( A->Stype == NR ) {
	Destroy_SuperMatrix_Store(AA);
	SUPERLU_FREE(AA);
    }

    /* ------------------------------------------------------------
       Print timings, then deallocate statistic variables.
       ------------------------------------------------------------*/
    PrintStat(&Gstat);
    StatFree(&Gstat);
}
